High temperature greases



3,065,177 Patented Nov. 20, 19162 seesaw HIGH TEMPERATURE GREASES BruceW. Hotten, Grinds, Calh'r'., assignor to Caiiiornia Research orporation,San Francisco, tCaiiil, a corporation oi Delaware No Drawing. Filed Mar.14, 1960, get. No. 1 3 524 5 Claims. (Cl. 252--49.6)

This invention relates to lubricating greases. More particularly, itrelates to lubricating oil compositions composed of an oil oflubricating viscosity thickened by a thickening agent to grease-likeconsistency, such grease. being characterized by high melting points andwherein the thickening agent is nonmetallic.

This application is a continuation-impart of Hotten patent applicationSerial No. 606,993, filed August 30, 1956, and now abandoned.

It is prevailing practice to use salts of certain fatty acids or othersuitable acids and certain metals to produce high melting point greases.Thus, sodium and lithium stearates, also sodium and lithium salts of certain mono-amides of polycarboxylic acids are employed as thickeners toproduce high melting point greases. Metal salt thickeners aredisadvantageous, however, because the metals therein promote oxidation.

Although nonmetalcontaining grease thickening agents have been proposedhereto-fore, most of these do not produce grease compositions havinghigh dropping points (ASTM method D566-42).

It is an object of the present invention to provide greases having hi hdropping points and in which the thickeners are of the nonmetallic type.

It is a particular object of the invention to provide greases havingdropping points in the neighborhood of 400 F. or more, preferably 500 F.or more, and wherein the thickeners are nonmetallic.

Yet another object of the invention is to provide novel compounds whichcan be prepared economically, which are nonmetallic in nature and whichare useful, among other things, as grease thickeners.

These and other objects of the invention will be ap parent from theensuing description and the appended claims.

In accordance with the present invention, it has been discovered thathigh melting grease compositions are obmined by incorporating in certainpolysiloxane base oilsby the formula 1 ll II I (Rh H O O H wherein theRs are alkyl radicals containing from 1 to 3 carbon atoms, and n is anumber from to 1.

Esters of terepnthalarnic acids which are contemplated herein incombination with terephthaldiamides include those of the formula whereinrepresents hydrogen or the methyl or ethyl radicals, and R is an alkylradical containing from 1 t0 2 carbon atoms.

The preferred diamides of terephthalic acid are those having the typeformula The combination of terephthaldiarnides and terephthalamic acidsor their esters effectively thickens to grease consistency certainmethyl, phenyl polysiloxanes. These oils are characterized aspolymethylphenylsiloxanes having a medium methyl-phenyl ratio. Asdetermined by the infrared analysis procedure described in NavalResearch Laboratory Report, P-2746 (1946), by Smith, French and ONeil,the methylphenyl ratios are evaluated according to the peaks observed inthe infrared analysis; these ratios have values from 0.3 to 0.5; thatis. the methyl radicals and the phenyl radicals are present in thepolyrnethylphenylsiloxane in proportions such that the ratio of methylradicals to phenyl radicals has values from 0.3 to 0.5, based oninfrared analysis.

The combination of terephthaldiami es and terephthaiarnic acids (oresters th reof) is used in amounts of 15%, by weight, to 50%, preferably20% to 30%. The weight ratio of tcrephthaldiarnides to terephthalamicacids (or esters thereof) is from 1:4 to 1:1.

The thickener combination of the invention may be incorporated in suchbase oils in varying amounts. Where a high dropping point is notimportant, the combination may be used in amounts as low as 5%, or lessmay be employed, but "t /here high dropping points (i.e., about 500 F.or higher) are desired, larger amounts of thickener combination shouldbe employed, for example, or higher, all such percentages being byweight based on the finished grease. It is preferred to use no more than30%. All percentages are by weight based on finished product.

The following specific examples will serve to illustrate the practiceand advantages of the invention.

EXAMPLE I 5 Mixture of N,N'-Di-p-Tolylterepht/mldiamide andN-Zolylterephthalamic Acid 1284 grams (l2 mols) of p-toluidine and 582grams (3 mols) of dimethyl terephthaiate were heated and stirredtogether at l70210 C. for 6 hours. The prodnot was washed three timeswith boiling benzene and was dried. A yield of 733 grams was obtainedconsisting of one-half N,N-di-p-tolyiterephthaldiamide and one-ha1fN-tolylterephthalarnic acid having the following formulas:

N,N-di-p-tlylterephthaldiamide HO-CO-QCO-NH-Q-Olia N-tolylterephthalamicacid The saponification number of the product was 154 and nitrogencontent was 6.54%.

EXAMPLE II and 500+ F.; worked pentration (P of 348; and a high speedbearing life of 510 hours (average of two runs, 354 and 665 hours) at450 F. and of 307 hours (average of two runs, 212 and 401 hours) at 500F. The high speed bearing life test (quoted as MILG25013) was run asfollows:

A 204K Conrad type 8-ball bearing packed with grease was operated at10,000 rpm. continuously for 22 hours at the designated temperature. Thebearing was then cooled to room temperature during a period of 2 hours,'then run at 10,000 r.p.m. for another 22 hours. This cycle was repeateduntil the bearing failed.

Other greases containing thickener combinations of this invention areillustrated, together with test results, in Table I hercinbelow. Thecompositions were blended and treated by processes similar to those setforth in E ample II hereinabove.

The base oil in each of the compositions A, B, C, D and E was apolymethylphenylsiloxane wherein the methyl-phenyl ratio had a value of0.4 (based on infrared It will, therefore, be apparent that nonmetallicgrease thickeners described herein form greases which are characterizedby high dropping points and, in many cases by exceptionally highdropping points. The latter characteristic is highly advantageous inview of the fact that the thickeners are nonmetallic.

Such greases may include other ingredients, such as oxidation and/ orcorrosion inhibitors, etc.

I claim:

1. A grease composition comprising a major proportion of a polysiloxanebase oil of lubricating viscosity and, in an amount sufficient tothicken said oil to the consistency of a grease, the combination of aterephthaldiamide having the type formula in M wherein the Rs are alkylradicals containing from 1 to 3 carbon atoms, and n is a number from 0to 1, and a compound of the formula wherein R is selected from the groupconsisting of hydrogen and alkyl radicals containing from 1 to 2 carbonatoms, and R is an alkyl radical containing from 1 to 2 carbon atoms,wherein said polysiloxane is a polymethylphenylsiloxane wherein themethyl-phenyl ratio has values from 0.3 to 0.5, and the weight ratio ofterephthaldiamide to said compound is from 1:4 to 1:1.

2. A grease composition consisting essentially of apolymethylphenylsiioXane base oil and, from to by weight, of thecombination of a terephthaldiamide of the formula h o in).

wherein the Rs are alkyl radicals containing from 1 to 3 TABLE I Amount,ASTM Bearing Composition Wt. Appearance Dropping P Life Percent Point,(Hours) a ass i 5 (b) Terephthalyl-di-p-toluidide 25 i B (a) Base Oil 75do (b) Methyl,N-p-tolylterephthalamate 25 O (a) Base Oil 75 (b)Terephthalyl-di-p-toluidide. 12.5 Smooth Grease 494 382 l 529 (c)Methyl,N-p-tolylterephthalarnat 12.5

D (a) Base Oil 75 (b) Terephthalyl-di-p-toluidide do 500 348 l 307 (c)N-p-tolylterephthalamic acid 12.5

E (a) Base Oil 75 (b) Terephthalyl-di-p-toluidide- 18.75 d0 367 (c)N-tolylterephthalamic acid 6.25

F (a) Base oil 75 (b) Terephthalyi-di-p-toluidide 125 do 404 (c)N-p-tolylterephthalamie acid 12.5

1 Average of 2 runs.

carbon atoms, and n is a number from 0 to 1, and a compound of theformula wherein the Rs are alkyl radicals containing from 1 to 3 carbonatoms, and n is a number from 0 to 1, and a compound of the formulawherein R is selected from the group consisting of hydrogen and alkylradicals containing from 1 to 2 carbon atoms, and R is an alkyl radicalcontaining from 1 to 2 carbon atoms, wherein the methyl-phenyl ratio ofsaid polysiloxane has values from 0.3 to 0.5, and wherein the weightratio of said terephthaldiamide to said compound is from 1:4 to about1:1.

4. A grease composition comprising a major proportion of apolymethylphenylsiloxane base oil, and from 20% to 30%, by weight, ofthe combination of a terephthaldiamide ofN,N-di-p-to1yltercphthaldiamide and N- tolylterephthalamic acid, whereinthe terephthaldiamideterephthalamic acid weight ratio is from 1:4 to1:1.

5. A grease composition comprising a major proportion of apolymethylphenylsiloxane base oil, and from 20% to 30%, by weight, ofthe combination of equal parts, by weight, ofN,N'-di-p-tolylterephthaldiamide and N- tolylterephthalamic acid,wherein the methyl-phenyl ratio of said polymethylphenylsiloxane hasvalues from 0.3 to 0.5.

References Cited in the file of this patent UNITED STATES PATENTS

1. A GREASE COMPOSITION COMPRISING A MAJOR PROPORTION OF A POLYSILOXANE BASE OIL OF LUBRICATING VISCOSITY AND, IN AN AMOUNT SUFFICIENT TO THICKEN SAID OIL TO THE CONSISTENCY OF A GREASE, THE COMBINATION OF A TEREPHTHALDIAMIDE HAVING THE TYPE FORMULA 